Tracking issue for `pub(restricted)` privacy (RFC #1422)

[nikomatsakis]

Tracking issue for rust-lang/rfcs#1422

RFC text

Milestones:

• Implemented (PR Implement pub(restricted) privacy (RFC 1422) #32875)
• Decided to stabilize
• Update syntax Update syntax for pub(restricted) #40340
• Documented in the rust manual document pub(restricted) syntax #40334
• Stabilization PR -- see mentoring instructions below
• Stabilized

[jonas-schievink]

You probably meant rust-lang/rfcs#1422

[nikomatsakis]

@jonas-schievink indeed. :)

[petrochenkov]

How to parse struct S(pub (std::marker::Send + std::marker::Sync));? It's currently legal.

If we try to parse std::marker::Send as a part of pub(restricted) based on is_path_start(std) == true, then we end up in the middle of a type sum after parsing an arbitrary number of tokens with only a Path in hands and need to recover.

Similar cases with simpler disambiguation:

struct Z(pub (u8, u8));
struct W(pub (u8));

Note that pub(path) is a strict subset of pub TYPE (modulo pub(crate)), so the former can be parsed as the latter and reinterpreted later if necessary.

I suppose everything here can be disambiguated, but I'm concerned about the conflict pub(path) vs pub TYPE in general and how it affects formal properties of Rust grammar.

[nikomatsakis]

@petrochenkov sigh. a very good point. @pnkfelix and I were chatting-- one obvious (but not particularly appealing) option would be to say that tuple structs just can't use pub(restricted) paths. This would be better if we had the notion that one could write struct Z { pub 0: (u8, u8) } to use the more explicit name.

We considered various other synaxes one could use:

• pub{path}
• pub(in path)
• pub in path

One consideration is that I expect most people will want to either make fields pub -- meaning, as public as the struct itself -- or private. So perhaps it's ok that you can't use tuple structs to express more flexible things -- they're kind of a convenience shorthand as is. But it is unfortunate however you slice it.

[Stebalien]

For reference, @nikomatsakis is referring to #1506.

[nikomatsakis]

On Sun, Apr 3, 2016 at 5:52 AM, Vadim Petrochenkov <notifications@github.com

wrote:

Note that pub(path) is a strict subset of pub TYPE (modulo pub(crate)),
so the former can be parsed as the latter and reinterpreted later if
necessary.

Hmm, I suppose that's true. (Or might be true)